Henri Brocard

Pierre René Jean Baptiste Henri Brocard ( born May 12, 1845 in Vignot, Canton COMMERCY; † January 16, 1922 in Bar- le- Duc) was a French mathematician and military officer.

Brocard visited the schools ( lyceums ) in Marseille and Strasbourg and studied from 1865 to 1867 at the Ecole Polytechnique. He was then as an engineer officer and meteorologist in the French army. In the war of 1870 he took part in the Battle of Sedan, where he was taken prisoner. Later he was stationed in Algiers and again in 1884 in France as a meteorologist in Montpellier, Grenoble and Bar-le- Duc. In 1910 he went as a Lieutenant (Lieutenant Colonel ) in the retired and lived in Bar- le- Duc, where he lived alone and withdrawn and Librarian of the Society for Literature, Arts and Sciences was. The proffered presidency of the society he refused. He dedicated himself retired and astronomical observations.

He joined soon after its formation in 1873 of the French Mathematical Society and was advancement of the sciences ( Afas ) since 1875 Member of the Association Française pour l'. Brocard regularly visited the International Mathematical Congresses since of Zurich 1897.

Brocard is known for studies on the geometry of triangles, among others, are Brocard points named after him, which he published. Brocard points, however, were introduced in 1817 by August Leopold Crelle in Germany, but fell into oblivion. Berkhan and Wilhelm Franz Meyer dated the resurgence of interest in triangle geometry in the second half of the 19th century to a task of Brocard in 1875, and a lecture by Émile Lemoine before Afas 1873. According Brocard are also Brocard circle Brocard diameter, Brocard angle ( clearly the specific angle in the design of Brocard point) designated.

He is also known for various conjectures and problems in number theory. The problem of Brocard ( Brocard 1876, 1885) is to find numbers n for which a natural number m. Are known only to the solutions n = 4,5,7 and it is believed that there are no further (Paul Erdos ). The Brocardsche guess is related to the Legendre 's conjecture: at least four primes between the squares of consecutive primes. The problem and the conjecture of Brocard are unresolved.

Brocard was an officer of the Legion of Honour.

Writings

• Etudes d'un nouveau cercle du plan du triangle. Assoc. Français pour l' advancement of the sciences, Congrès d' Alger, Volume 10, 1881, pp. 138-159
• Notices sur les titres et travaux scientifique, Bar-le- Duc in 1895
• Notes de bibliography of courbes géométriques, Bar le Duc, 1897, 1899, 2 volumes. The book appeared in only about 50 copies and contains information on around 1000 curves.
• With T. Lemoyne: Courbes géométriques remarquables, 2 volumes, Paris, Volume 1, 1920, 1967 ( new edition ), Volume 2, 1967
• Continued with E. Vigarié the historical- bibliographical report on triangle geometry of E. Lemoine, reports ( Compte rendu ) the Afas, 1885, 1889, 1895, 1906